This invention relates to a shaker mechanism for wheeled vehicles, e.g., trucks, tractors or trailers. Generally similar shaker mechanisms are shown in U.S. Pat. Nos. 3,459,037 and 3,828,614 and 4,527,416.
A typical vehicle shaker mechanism comprises four (or more) upright fluid cylinder actuators spaced apart in accordance with the vehicle wheel centerline dimensions and axle length dimensions. The number of actuators is a function of the number of axles on the vehicle. The cylinder actuators may be located in a pit or floor area of a test facility. The test vehicle is centrally positioned above the cylinders, such that each cylinder supports one of the vehicle axles (or outboard end areas of the axles).
The fluid cylinders are selectively energized to impart shaking forces to the vehicle axles. In many cases the cylinders are programmed or controlled by computer tapes, to provide standardized reproducible vehicle testing procedures and test results. In a typical situation the tape generates electric signals that are applied to electrically-operated valves controlling fluid flow to/from different ones of the fluid cylinders (actuators).
The various valves are selectively opened and closed to produce fluid cylinder motions, varied as to speed, stroke and frequency, according to the taped program. The vehicle undergoes a shaking action designed to equal or exceed rough terrain operations.
During the shaking operations it is necessary that the vehicle be rigidly attached to the fluid cylinder actuators; otherwise the vehicle will be displaced laterally off the actuators, with consequent destructive effects. Usually each axle is firmly clamped to the associated actuator. Additionally tie rods or chains may be connected between points on the vehicle frame and wall areas of the test facility (as added assurance that the vehicle will not shift horizontally). In some cases the horizontal tie rods take the form of fluid cylinder actuators that can be used to apply horizontal forces to the vehicle.
Shaker mechanisms have been proposed for use in testing various types of military vehicles including dump trucks, tractors, trailers, cargo carriers, fuel tank trucks, flat bed trucks, vans, bridge transporters, ammunition carriers, personnel carriers, radio command cars, etc. Such vehicles may vary in weight, overall length, axle length, and axle centerline spacing. The variable characteristics make it somewhat difficult for a given test facility to be readily or quickly adjusted to accommodate differently sized vehicles. As a result, it has not always been possible to test a given vehicle when it was desired to do so.
The present invention is directed to a shaker mechanism that can be used to test a wide variety of different vehicles, with minimal need for costly or time-consuming adjustments to the shaker mechanism or to the vehicles undergoing test.
One object of the invention is to provide a shaker mechanism that connects with axle areas of a vehicle, to thereby permit the tested vehicle to shake or move substantially in the same manner (or to the same extent) as it would during actual rough terrain operations. The vehicle components (e.g., suspension springs, axles, frame, engine mounts, etc.) are subjected to the same (or greater) forces that they would be exposed to in actual service. The test becomes a realistic test that can be confidently used to predict vehicle component performance (or non-performance).
A further object of the invention is to provide a shaker mechanism that can be rigidly and firmly attached to the axles of test vehicles, thereby minimizing possible displacement of the vehicle from the shaker mechanism.